The 3rd Generation Partnership Project (3GPP) covers cellular telecommunications network technologies, including radio access, the core transport network, and service capabilities. The latest version of the 3GPP mobile core network (MCN) architecture for wireless communications is referred to as the Evolved Packet Core (EPC). The Evolved Packet Core (EPC) has a “flat architecture” to handle the data traffic efficiently from performance and cost perspective. EPC also separates the user data (also known as the user plane) and the signaling (also known as the control plane) to allow the EPC's control and data planes to scale independently.
FIG. 1 is a basic architecture diagram illustrating User Equipment (UE) 104 (e.g., a mobile phone or other wireless device) connectable to a Mobile Core Network (MCN) 102, such as an EPC, and connectable to a local network 128 through a L-GW 130.
In this diagram, the UE 104 connects to a Small Cell Access Point (SC-AP) 106. Small Cell Access Point (SC-AP) 106 is a low-powered radio access node with a range that is small compared to a mobile macrocell. The Small Cell Access Point (SC-AP) 106 can be designed for deployment in small coverage areas such as indoors or for small public hotspots. Small cells include femtocells having a range on the order of 10 meters. In 3GPP, SC-APs include a Home Node B (HNB), which is a 3G femtocell, and a Home eNode B (HeNB), which is an LTE (Long Term Evolution) femtocell.
Security Gateway (SeGW) 108 is shown in the MCN 102. The Security Gateway 108 establishes an IPsec tunnel 110 with the SC-AP 106. Internet Protocol Security (IPsec) is a protocol suite for securing Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a communication session. In tunnel mode, IPsec encrypts the entire IP packet including headers. These encrypted IP packets are then encapsulated into new IP packets with new IP headers. The IPsec tunnel 110 passes through the backhaul 124 which includes intermediate network links between the SC-AP 106 and MCN 102.
The Small Cell Gateway (SC-GW) 112 aggregates traffic from multiple Small Cell Access Points, including SC-AP 106, into the MCN 102. In FIG. 1, the SC-AP 106 is connected using an S1 User (S1-U) interface to the SC-GW 112.
Serving Gateway (S-GW) 114 and Packet Data Network Gateway (PDN-GW) 116 deal with the user plane. They transport IP data traffic between the User Equipment (UE) 104 and external networks, such as Packet Data Network (PDN) 118. The Serving GW 114 is the point of interconnect on the radio side. In this case, the S-GW 114 is connected through the SC-GW 112. Serving Gateway 114 serves the UE 104 by routing incoming and outgoing IP packets. The S-GW 114 is connected to the PDN GW 116.
The PDN GW 116 is the point of interconnect between the MCN 102 and external networks PDN 118. PDN 118 can be an IP network, such as the Internet. The PDN-GW 116 routes packets to and from PDNs, such as PDN 118.
The MME (Mobility Management Entity) 120 deals with the control plane. It handles the signaling related to mobility and security. The MME 120 is responsible for the tracking and the paging of UEs in idle-mode. It is also the termination point of the Non-Access Stratum (NAS) messaging.
The HSS (Home Subscriber Server) 122 is a database that contains user-related and subscriber-related information. It also provides support functions in mobility management, call and session setup, user authentication and access authorization.
The Policy and Charging Rules Function (PCRF) 126 determines policy rules of the network in real time. The PCRF 126 accesses subscriber databases and other specialized functions, such as a charging system, in a centralized manner.
The MCN 102, such as an EPC, can provide Quality of Service (QoS) to users who access content over the Packet Data Network (PDN) 118, such as the Internet. The PDN connection of UE 104 through the MCN 102 can be configured to provide various levels of QoS.
The SC-AP 106 also has the capacity to connect to a local network 128 through a Local Gateway (L-GW) 130. In this way, the User Equipment 104 can use resources at the local network 128, such as office printers, without routing through the MCN 102. The L-GW 130 can be integrated with the SC-AP 106 or be a standalone box.
In R12 of 3GPP, the E-UTRAN/EPC architecture includes a feature called Selected Internet IP Traffic Offload at the Local Network (SIPTO@LN). SIPTO@LN can be used to allow the UE to 104 connect through an L-GW 130 to the Internet. The SIPTO@LN feature allows the MME 120 to direct the UE 104 to break a PDN connection that is currently anchored to P-GW 116 in the MCN 102 and establish a new PDN connection that is anchored to the L-GW 130. The new PDN connection with the L-GW 130 can then be used by the UE 104 to access the Internet. The traffic from the UE 104 is thus offloaded from the backhaul 124 and MCN 102.
Edge caching is discussed in the Small Cell Forum's document SCF088. One example use case describes an Small Cell Network (SCN) deployed in a shopping mall. The SCN offers caching services to content providers. The content provider may offer web accessible advertisements, videos, web pages, etc. The content provider is able to cache content in the SCN, thus providing more efficient (lower latency) access to the user and offloading traffic from the back haul and mobile core network.
In the Small Cell Forum's document SCF088, the Small Cell Forum created a basic architecture framework for supporting edge caching. The framework is shown in FIG. 2.
The architecture of FIG. 2 shows that the caching service consists of four main components—the Edge Server(s) 202, the Local Mapping Service 204, the Management Portal 206 and the Local Data Collection and Analytics Service 208. The edge server(s) 202 are used to store cached content. The local mapping service 204 checks if requests from the UE 210 are available in the local edge server 202 and directs the UE 210 to the cached content. The local mapping service 204 may explicitly redirect the UE 210 to the cached content or transparently forward the UE's request to the edge server 202. In other words, when explicit methods of redirection are used, the UE 210 is aware that it is accessing cached content and when transparent methods of redirection are used, the UE 210 is not aware that it is accessing cached content.
The management portal 206 is used by content providers to load content/data into the edge server(s) 202 of the small cell network. Content placement methods may be transparent or explicit/directed. An explicit method of loading content would be when a content provider intentionally loads content into the edge server for future retrieval. Transparent methods are used when the network autonomously decides to create a cached copy of some remote content.
The management portal 206 may also be used to access the local data collection and analytics service 208. The local data collection and analytics service 208 can be used by the original content provider to manage any content that is cached in the edge servers 202 and to view analytics, or statistics, about how such content is accessed.
With the foregoing as background information, the present application discloses a new method and system for caching content in a mobile core network.